This invention relates generally to a magnetic recording medium such as a magnetic disk, and more particularly the invention relates to a magnetic recording media having a ternary or quaternary alloy seedlayer.
The magnetic disk drive as used for data storage and computer systems comprises one or more disks having thin film magnetic layers on opposing surfaces for the recording of magnetic data as bits along concentric tracks. Typically, as shown in FIG. 1, the disk comprises a substrate 4 of nickel phosphorus (NiP) or ceramic glass on which a plurality of layers are formed by sputtering in a low pressure inert gas atmosphere. The layers include a magnetic seedlayer 6, a nonmagnetic underlayer 8 of either pure chromium (Cr) or a chrome alloy (CrX), covered by a magnetic layer 10 of a cobalt (Co)-based alloy. A protective layer 12 made of sputtered carbon (C) is typically placed on top of the magnetic layer and an organic lubricant 14 may be used on top of the protective layer.
Disclosed and claimed in U.S. Pat. No. 5,693,426 is a magnetic recording medium with an underlayer having a B2 structured crystal lattice and a cobalt-based magnetic layer. The B2 ordered crystalline structure is described as providing a lighter, smaller and better performing magnetic storage medium. The B2 structure is further described as an ordered structural derivative of the body centered cubic (bcc) structure, which is the structure of chromium. A nickel aluminum alloy (NiAl) and other two element alloys are described as providing the B2 lattice structure.
The present invention is directed to providing a magnetic recording medium with improved magnetic performance including coercivity (Hr), remanent magnetization (Mrt), and coercive squareness (S*) without the use of an underlayer having a B2 crystalline structure.